class_docstr: A Model is a network (more precisely, a directed acyclic graph) of Steps,
  and it is defined from the input/output specification of the pipeline.
  Models have fit and predict routines that, together with graph-based engine,
  allow the automatic (feed-forward) computation of each of the pipeline steps
  when fed with data.
  
  Parameters
  ----------
  inputs
      Inputs to the model.
  
  outputs
      Outputs of the model.
  
  targets
      Targets of the model.
  
  name
      Name of the model (optional). If no name is passed, a name will be
      automatically generated.
docstr: Get the graph associated to the model.
docstr_tok: ["Get","the","graph","associated","to","the","model","."]
code: def graph(self):
      """Get the graph associated to the model."""
      return self._graph
  
imports: from collections import defaultdict
  from typing import Union, List, Dict, Set, Iterable, Optional
  from baikal._core.data_placeholder import is_data_placeholder_list, DataPlaceholder
  from baikal._core.digraph import DiGraph
  from baikal._core.step import Step, InputStep, Node
  from baikal._core.typing import ArrayLike
  from baikal._core.utils import listify, safezip2, SimpleCache, unlistify
label_desc: Use image node_id 18 for calling the Model obj's underlying member method code with example usage: obj.graph() and returns: self